Android KeyStore Initialization

问题

First off I am new to android Programming, though I am not new to programming itself. What I am, essentially, trying to do is to save my encryption Keys into the Android Keystore. There seems to be a phenomenal lack of such information on GOOGLE, itself. Since there is not much how-to available on the topic I am assuming that it isn't fairly standard knowledge. So can someone please give me a sample code to

Initialize the KeyStore(Will be using AES-256).
Save multiple keys in a KeyStore(Please tell me the max number of keys I can store in 1 KeyStore, since i plan on saving nothing short of a 100).
Get Keys from KeyStore.
Edit Keys
Delete Keys
Delete Entire KeyStore

So in essence a code for all basic functions of a keystore. Thank you in advance for your assistance.

回答1:

If you set your minSdkVersion to 23 or higher Android M makes it easy to generate and manage symmetric keys as of this month.

Check out the 4th example listed here. https://developer.android.com/reference/android/security/keystore/KeyGenParameterSpec.html

 KeyGenerator keyGenerator = KeyGenerator.getInstance(
         KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore");
 keyGenerator.initialize(
         new KeyGenParameterSpec.Builder("key2",
                 KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT)
                 .setBlockModes(KeyProperties.BLOCK_MODE_GCM)
                 .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
                 .build());
 SecretKey key = keyGenerator.generateKey();

 Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
 cipher.init(Cipher.ENCRYPT_MODE, key);
 ...

 // The key can also be obtained from the Android Keystore any time as follows:
 KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
 keyStore.load(null);
 key = (SecretKey) keyStore.getKey("key2", null);

This example also was helpful. https://github.com/googlesamples/android-ConfirmCredential/blob/master/Application/src/main/java/com/example/android/confirmcredential/MainActivity.java

回答2:

I think Android Key Store does not support symmetric keys like AES keys. Please refer to here. BTW, why does the app need so many symmetric keys? I suggest that you store one master asymmetric key in key store, and use this key to encrypt many other symmetric keys in your app. Hope you solve your problem soon.

来源：https://stackoverflow.com/questions/28804307/android-keystore-initialization

标签

android

encryption

cryptography

aes

keystore